FreeSWITCH is an open source telephony platform designed to
facilitate the creation of voice and chat driven products scaling from a
soft-phone up to a soft-switch. It can be used as a simple switching
engine, a PBX, a media gateway or a media server to host IVR
applications using simple scripts or XML to control the callflow.

It supports various communication technologies such as Skype, SIP, H.323
and GoogleTalk making it easy to interface with other open source PBX
systems such as sipXecs, Call Weaver, Bayonne, YATE or Asterisk.

FreeSWITCH supports many advanced SIP features such as presence/BLF/SLA
as well as TCP TLS and sRTP. It also can be used as a transparent proxy
with and without media in the path to act as a SBC (session border
controller) and proxy T.38 and other end to end protocols.

FreeSWITCH supports both wide and narrow band codecs making it an ideal
solution to bridge legacy devices to the future. The voice channels and
the conference bridge module all can operate at 8, 12, 16, 24, 32 or 48
kilohertz and can bridge channels of different rates.

FreeSWITCH builds natively and runs standalone on several operating
systems including Windows, Max OS X, Linux, BSD and Solaris on both 32
and 64 bit platforms.